A method developed in this laboratory for determining the volume velocity or airflow waveform at the glottis by inverse-filtering the volume velocity at the mouth will be applied to a number of problems relating to voice quality and the role of the larynx in speech production. Specific areas to be studied are: (1) the variation of the glottal waveform with forced changes of transglottal pressure designed to leave the laryngeal adjustment invariant, (2) the variation of the glottal waveform during voluntary changes of subglottal pressure in speech-like utterances, (3) the relationship between the glottal area waveform and the glottal airflow waveform during voicing, and (4) the control of movements of glottal abduction and glottal adduction in the speech of deaf. Also to be studied are technical problems in inverse-filter adjustment.